1. Field Of The Invention
This invention relates to water flow meters and is more particularly directed to prevent the loss of oil and seepage of water into the water flow meter due to changes in pressure and temperature.
2. Description Of The Prior Art
In order to maintain the counter mechanism in a conventional water flow meter properly lubricated and to prevent the seepage of water therein, the meter housing is filled with lubricating oil. However, due to temperature and pressure changes subjected onto the water flow meter, the oil contained in the housing will expand and contract. When the oil, with or without air trapped also in the housing, expands there must necessarily be a discharge of excess oil through the seal which normally occurs at the propeller shaft where it leaves the housing. Now when there is a change in pressure and temperature to cause the oil to contract, a partial vacuum will be formed in the housing to cause the higher atmosphere or water pressure to force air or water into the housing until the pressures within and external of the housing are balanced. This exposure of the water flow meter to variations of pressure and temperature causes the device to effect a pumping action whereby oil in the meter housing becomes contaminated with water and air. For this reason, it becomes necessary for the conventional water flow meters to be evacuated of its oil at each use to remove the contaminated oil in order to have a properly operating meter and prevent the deterioration of its counter mechanism. The present invention contemplate avoiding the above indicated objection to the conventional water flow meter by providing a pressure and temperature controlled device within the meter that prevents the loss of oil due to such changes in temperature and pressure to which the water flow meters are normally subjected.